I don't actually agree with a universal child payment. It's a bit of a waste really. If we're trying to have a poverty baseline under which no one falls then money should be targeted. I don't see the point in giving money to parents who are either swimming in it or even just coping. I'd rather money be spent on those most in need. It's the whole point of have a welfare state - having a safety net for those that need it, not to make life a little bit easier for those who are already coping.
And from a larger societal point of view, giving money to those who don't need it is silly, it takes money out of circulation - it'll get put into a savings account or some such. Whereas if you give it to those who needed it, they'll spend it - more money in the system, better all round. That's not really the point though. The point is that that if it's not targetted, then there's more wastage than there needs to be.